/* ==========================================================================
   Stardust Cloud (星尘云) - CSS Design System & Theme Styles
   Domain: stardustcloud.mom
   ========================================================================== */

:root {
  --bg-dark: #070913;
  --bg-card: rgba(15, 23, 42, 0.65);
  --bg-card-hover: rgba(30, 41, 59, 0.8);
  --border-glow: rgba(56, 189, 248, 0.2);
  --border-glow-hover: rgba(56, 189, 248, 0.5);
  --primary-blue: #3b82f6;
  --cyan-glow: #38bdf8;
  --purple-glow: #8b5cf6;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Microsoft YaHei", sans-serif;
  --shadow-glow: 0 0 25px rgba(56, 189, 248, 0.15);
  --shadow-glow-hover: 0 0 35px rgba(56, 189, 248, 0.35);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-family: var(--font-family);
  background-color: var(--bg-dark);
  color: var(--text-main);
  overflow-x: hidden;
}

body {
  position: relative;
  min-height: 100vh;
  line-height: 1.6;
}

/* Background Stardust Canvas Layer */
#stardust-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -2;
  pointer-events: none;
}

/* '夜观星尘' (Stargazing Night Cosmic Sky) Background Layers */
.ambient-nebula {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  background: 
    /* Milky Way Stardust Ribbon Gradient (倾斜银河星尘带) */
    linear-gradient(125deg, rgba(3, 5, 17, 0.95) 0%, rgba(11, 16, 38, 0.9) 35%, rgba(30, 27, 75, 0.4) 60%, rgba(7, 9, 19, 0.95) 100%),
    /* Deep Cosmic Night Glow (夜空弧光) */
    radial-gradient(ellipse at 50% 10%, rgba(56, 189, 248, 0.22) 0%, transparent 60%),
    radial-gradient(circle at 80% 40%, rgba(139, 92, 246, 0.25) 0%, transparent 50%),
    radial-gradient(circle at 20% 70%, rgba(14, 165, 233, 0.18) 0%, transparent 45%);
  animation: stargazingPulse 14s ease-in-out infinite alternate;
  pointer-events: none;
}

/* Stargazing Mountain Ridge Silhouette (夜观星空山脊剪影) */
.stargazing-horizon {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 180px;
  z-index: -1;
  pointer-events: none;
  background: radial-gradient(ellipse at 50% 100%, rgba(15, 23, 42, 0.8) 0%, transparent 80%);
}

.stargazing-horizon::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 120px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 120' preserveAspectRatio='none'%3E%3Cpath d='M0,120 L0,60 Q150,20 300,70 T600,40 T900,80 T1200,30 L1200,120 Z' fill='%2303050a' opacity='0.85'/%3E%3Cpath d='M0,120 L0,80 Q200,40 400,90 T800,50 T1200,75 L1200,120 Z' fill='%23070913' opacity='0.95'/%3E%3C/svg%3E");
  background-size: 100% 100%;
  background-repeat: no-repeat;
  opacity: 0.9;
}

@keyframes stargazingPulse {
  0% {
    opacity: 0.8;
    transform: scale(1);
  }
  50% {
    opacity: 1;
    transform: scale(1.03);
  }
  100% {
    opacity: 0.85;
    transform: scale(1.01);
  }
}

/* Typography & Gradient Text */
.gradient-text {
  background: linear-gradient(135deg, #ffffff 0%, #bae6fd 35%, #38bdf8 70%, #60a5fa 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

.gradient-subtext {
  background: linear-gradient(135deg, #e2e8f0 0%, #94a3b8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

a {
  color: var(--cyan-glow);
  text-decoration: none;
  transition: all 0.3s ease;
}

a:hover {
  color: #60a5fa;
  text-shadow: 0 0 8px rgba(56, 189, 248, 0.4);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header Navigation */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(7, 9, 19, 0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  padding: 16px 0;
  transition: all 0.3s ease;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 22px;
  font-weight: 800;
  letter-spacing: 0.5px;
}

.logo-svg {
  width: 36px;
  height: 36px;
  filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.6));
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 15px;
}

.nav-links a:hover {
  color: #ffffff;
}

.nav-btns {
  display: flex;
  align-items: center;
  gap: 14px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 50px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid transparent;
}

.btn-primary {
  background: linear-gradient(135deg, #0284c7 0%, #2563eb 100%);
  color: #ffffff;
  box-shadow: 0 4px 20px rgba(37, 99, 235, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 28px rgba(56, 189, 248, 0.6);
  color: #ffffff;
}

.btn-glow {
  background: linear-gradient(135deg, #38bdf8 0%, #3b82f6 50%, #8b5cf6 100%);
  color: #ffffff;
  box-shadow: 0 0 20px rgba(56, 189, 248, 0.5);
}

.btn-glow:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: 0 0 30px rgba(56, 189, 248, 0.8);
  color: #ffffff;
}

.btn-outline {
  background: rgba(255, 255, 255, 0.05);
  color: #e2e8f0;
  border-color: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
}

.btn-outline:hover {
  background: rgba(56, 189, 248, 0.15);
  border-color: var(--cyan-glow);
  color: #ffffff;
}

.btn-recommend {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: #ffffff;
  box-shadow: 0 4px 15px rgba(245, 158, 11, 0.3);
}

.btn-recommend:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 25px rgba(245, 158, 11, 0.5);
  color: #ffffff;
}

/* Hero Section */
.hero {
  padding: 180px 0 90px;
  text-align: center;
  position: relative;
}

.badge-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 18px;
  border-radius: 50px;
  background: rgba(56, 189, 248, 0.1);
  border: 1px solid rgba(56, 189, 248, 0.3);
  color: var(--cyan-glow);
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 24px;
  box-shadow: 0 0 15px rgba(56, 189, 248, 0.1);
}

.badge-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: #10b981;
  box-shadow: 0 0 8px #10b981;
}

.hero-title {
  font-size: 54px;
  font-weight: 900;
  line-height: 1.2;
  margin-bottom: 24px;
  letter-spacing: -1px;
}

.hero-subtitle {
  font-size: 20px;
  color: var(--text-muted);
  max-width: 800px;
  margin: 0 auto 40px;
}

.hero-ctas {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
  margin-bottom: 50px;
}

/* Live Stats Bar */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  backdrop-filter: blur(12px);
  border-radius: 20px;
  padding: 30px;
  margin-top: 30px;
  box-shadow: var(--shadow-glow);
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-size: 36px;
  font-weight: 800;
  color: #ffffff;
  margin-bottom: 6px;
  font-family: monospace, var(--font-family);
}

.stat-label {
  font-size: 14px;
  color: var(--text-muted);
}

/* Section Common */
.section {
  padding: 90px 0;
  position: relative;
}

.section-header {
  text-align: center;
  max-width: 750px;
  margin: 0 auto 60px;
}

.section-title {
  font-size: 38px;
  font-weight: 800;
  margin-bottom: 16px;
}

.section-subtitle {
  font-size: 17px;
  color: var(--text-muted);
}

/* Floating Pricing Cards Requirement */
@keyframes floatAnimation {
  0% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-12px);
  }
  100% {
    transform: translateY(0px);
  }
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 28px;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 24px;
  padding: 36px 28px;
  backdrop-filter: blur(16px);
  transition: all 0.4s ease;
  position: relative;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-glow);
  
  /* Floating animation */
  animation: floatAnimation 5s ease-in-out infinite;
}

.pricing-card:nth-child(1) { animation-delay: 0s; }
.pricing-card:nth-child(2) { animation-delay: 1.2s; }
.pricing-card:nth-child(3) { animation-delay: 2.4s; }
.pricing-card:nth-child(4) { animation-delay: 3.6s; }

.pricing-card:hover {
  transform: translateY(-16px) scale(1.02) !important;
  border-color: var(--cyan-glow);
  box-shadow: var(--shadow-glow-hover);
  background: var(--bg-card-hover);
}

.pricing-card.popular {
  border-color: rgba(56, 189, 248, 0.7);
  background: rgba(30, 41, 59, 0.85);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #0284c7 0%, #38bdf8 100%);
  color: #ffffff;
  padding: 4px 16px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 700;
  box-shadow: 0 4px 12px rgba(56, 189, 248, 0.4);
}

.plan-name {
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 12px;
}

.plan-price {
  font-size: 42px;
  font-weight: 900;
  color: #ffffff;
  margin-bottom: 20px;
  display: flex;
  align-items: baseline;
  gap: 4px;
}

.plan-price span {
  font-size: 16px;
  font-weight: 400;
  color: var(--text-muted);
}

.plan-features {
  list-style: none;
  margin-bottom: 30px;
  flex-grow: 1;
}

.plan-features li {
  padding: 10px 0;
  color: #cbd5e1;
  font-size: 15px;
  display: flex;
  align-items: center;
  gap: 10px;
  border-bottom: 1px dashed rgba(255, 255, 255, 0.08);
}

.plan-features li:last-child {
  border-bottom: none;
}

.icon-check {
  color: #10b981;
  font-weight: bold;
}

/* Feature Grid */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 20px;
  padding: 30px;
  backdrop-filter: blur(12px);
  transition: all 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  border-color: rgba(56, 189, 248, 0.4);
  box-shadow: var(--shadow-glow);
}

.feature-icon {
  width: 54px;
  height: 54px;
  border-radius: 16px;
  background: rgba(56, 189, 248, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  color: var(--cyan-glow);
}

.feature-title {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
}

.feature-desc {
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.6;
}

/* Reviews / Testimonials Section */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.review-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 20px;
  padding: 28px;
  backdrop-filter: blur(12px);
}

.review-user {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.user-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, #0284c7 0%, #8b5cf6 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: #ffffff;
  font-size: 18px;
}

.user-info h4 {
  font-size: 16px;
  font-weight: 700;
}

.user-info p {
  font-size: 13px;
  color: var(--text-muted);
}

.stars {
  color: #f59e0b;
  margin-bottom: 12px;
  font-size: 14px;
}

.review-text {
  color: #cbd5e1;
  font-size: 14px;
  line-height: 1.6;
}

/* FAQ Accordion Section */
.faq-list {
  max-width: 850px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 16px;
  overflow: hidden;
  backdrop-filter: blur(12px);
  transition: all 0.3s ease;
}

.faq-question {
  padding: 22px 28px;
  font-size: 17px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

.faq-question:hover {
  color: var(--cyan-glow);
}

.faq-toggle-icon {
  font-size: 20px;
  transition: transform 0.3s ease;
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
  padding: 0 28px;
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.7;
}

.faq-item.active .faq-toggle-icon {
  transform: rotate(180deg);
}

.faq-item.active .faq-answer {
  max-height: 300px;
  padding: 0 28px 24px;
}

/* SEO Articles Section Grid */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 20px;
  overflow: hidden;
  backdrop-filter: blur(12px);
  transition: all 0.3s ease;
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  transform: translateY(-6px);
  border-color: var(--cyan-glow);
  box-shadow: var(--shadow-glow);
}

.article-body {
  padding: 26px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.article-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  color: var(--cyan-glow);
  background: rgba(56, 189, 248, 0.1);
  padding: 4px 12px;
  border-radius: 50px;
  margin-bottom: 14px;
  align-self: flex-start;
}

.article-title {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 12px;
  line-height: 1.4;
  color: #ffffff;
}

.article-excerpt {
  color: var(--text-muted);
  font-size: 14px;
  line-height: 1.6;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-link {
  font-size: 14px;
  font-weight: 600;
  color: var(--cyan-glow);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* Core Task 2: Low-profile Footer PBN Links styling */
.site-footer {
  background: #03050a;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding: 50px 0 30px;
  margin-top: 80px;
  text-align: center;
  position: relative;
}

.footer-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 18px;
  font-weight: 700;
}

.footer-nav {
  display: flex;
  gap: 20px;
  list-style: none;
  font-size: 14px;
  color: var(--text-muted);
}

.footer-copyright {
  font-size: 13px;
  color: #64748b;
  margin-top: 10px;
}

/* PBN Friendly Links Zone: Low-profile, integrated seamlessly */
.pbn-links-zone {
  margin-top: 24px;
  padding-top: 16px;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
  font-size: 12px;
  color: #475569;
}

.pbn-links-title {
  color: #475569;
  font-weight: 500;
}

.pbn-link-item {
  color: #64748b;
  text-decoration: none;
  transition: color 0.2s ease;
}

.pbn-link-item:hover {
  color: var(--cyan-glow);
}

/* Article detail page styles */
.article-page {
  padding: 140px 0 90px;
  max-width: 900px;
  margin: 0 auto;
}

.article-content {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: 24px;
  padding: 45px;
  backdrop-filter: blur(16px);
  line-height: 1.8;
  font-size: 16px;
}

.article-content h1 {
  font-size: 32px;
  margin-bottom: 20px;
  line-height: 1.3;
}

.article-meta {
  display: flex;
  gap: 20px;
  color: var(--text-muted);
  font-size: 14px;
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.article-content h2 {
  font-size: 24px;
  color: var(--cyan-glow);
  margin: 35px 0 18px;
}

.article-content h3 {
  font-size: 19px;
  color: #ffffff;
  margin: 25px 0 14px;
}

.article-content p {
  margin-bottom: 20px;
  color: #cbd5e1;
}

.article-content ul, .article-content ol {
  margin: 0 0 20px 24px;
  color: #cbd5e1;
}

.article-content li {
  margin-bottom: 8px;
}

.article-content blockquote {
  border-left: 4px solid var(--cyan-glow);
  padding: 16px 20px;
  background: rgba(56, 189, 248, 0.08);
  border-radius: 0 12px 12px 0;
  margin: 25px 0;
}

.article-nav-box {
  margin-top: 40px;
  padding: 24px;
  background: rgba(15, 23, 42, 0.8);
  border: 1px dashed var(--cyan-glow);
  border-radius: 16px;
}

.article-nav-box h4 {
  color: var(--cyan-glow);
  margin-bottom: 12px;
}

/* Responsive adjustments */
@media (max-width: 1024px) {
  .hero-title { font-size: 42px; }
  .feature-grid, .reviews-grid, .articles-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-bar { grid-template-columns: repeat(2, 1fr); gap: 16px; }
}

@media (max-width: 768px) {
  .nav-links { display: none; }
  .hero-title { font-size: 32px; }
  .hero-subtitle { font-size: 16px; }
  .feature-grid, .reviews-grid, .articles-grid { grid-template-columns: 1fr; }
  .stats-bar { grid-template-columns: 1fr; }
  .hero-ctas { flex-direction: column; width: 100%; }
  .btn { width: 100%; }
  .article-content { padding: 25px; }
}